I'm all for blaming the US for many things but I think dude is showcasing a biased view of the Hamas/Fatah conflict.
The US backed Fatah by 2007 and this backfired but Hamas already had the juice. In 2005, for the first time they participated in elections, they won, then they almost swept the 2006 elections for PA. And all that was for a reason.
In Arafat's later years and after his death, Fatah was rife with nepotism and corruption while Palestinians barely saw their conditions improved. Barghouti split from Fatah around that time because he was representing the young guard against the old one they were fed up with. And after 2006, Fatah refused to acknowledge Hamas' victory and that kickstared the war though both were already killing/kidnapping each other by then.
Part of the reason why Hamas became that strong in Gaza is because Fatah was ineffective and/or incompetent. Maybe Fatah would have won the war had they been united but realistically, they never were even under Arafat, there always were factions inside.
